The invention relates to an electronic telephone set. The set includes a transmission circuit for being coupled to a telecommunication network and for receiving and transmitting speech signals. The set also includes keyboard means comprising a first matrix with respective numbers of intersecting first and second conductors. At the intersections of the first and second conductors, key switches are coupled to the respective first and second conductors for producing dial information and status information. The keyboard means also includes a second matrix with one intersecting first and second conductor or a plurality thereof respectively. At selected intersections of the latter first and second conductors, setting circuits are coupled to the respective first and second conductors. The setting circuits conduct current in one and the same direction. All second conductors of the second matrix are arranged in common with those of the first matrix. The set also includes a control circuit arranged for generating dialling signals compatible with the telecommunication network in response to the dialling information produced by the keyboard means and controlling the operation of the telephone set in response to the status information produced by the keyboard means, which control circuit comprises scanning means for reading the two matrices.
Such an electronic telephone set is known from the publication of Philips Components Laboratory Report No. ETT 8805 by Jos Geboers and Hans van Loon, "Controller (PCD3344/006) Programmed for Telephone Sets with On-hook Dialling and up to 20 Number Repetory Dial Facilities", August 1988, Eindhoven, the Netherlands; specifically the block diagram on page 2 and FIG. 6 on page 8 with the relevant descriptions, especially part 4.9.2 of this report.
The transmission circuit may be an integrated circuit of the TEA 1060 family, whereas the control circuit may be an integrated circuit of the PCD 3340 family. The transmission circuit is arranged for being coupled to a telecommunication network, in the case described in the above report, by coupling its line terminals to a telephone line. Another option is that the transmission circuit is coupled to a transceiver means for radio connection to a telecommunication network. In the prior-art electronic telephone set the transmission circuit is fed from the line as is the control circuit via the transmission circuit. Alternatively, however, it is possible to have the above transmission and control circuits comprise a supply circuit which is line-independent or to feed the control circuit by means of a supply circuit, for example, the integrated circuit TEA 1081 mentioned in the publication referred to, which is used there for feeding an amplifier circuit, that is to say, the integrated circuit TEA 7050. In the prior-art electronic telephone set the transmission circuit receives speech signals from a microphone and delivers speech signals to an earphone.
Finally, the prior-art electronic telephone set comprises a keyboard means with a matrix of key switches for producing dial information, such as a telephone number. The control circuit reads the matrix of key switches and generates dial signals which are compatible with the telecommunication network, such as pulse dial signals or tone dial signals, in response to the dial information read. In the former case there is an electronic interruptor (BSN 254) inserted in the connection line between a line terminal of the transmission circuit and the telephone line, which interruptor is controlled by the pulse dial signals generated by the control circuit. In the latter case a tone dial generator (DTMF generator) comprised in the control circuit generates tone dial signals which are applied to the telephone line by means of the transmission circuit.
The keyboard means of the prior-art electronic telephone set also includes a matrix of setting units such as diodes (in the above publication referred to as diode straps) which are conductive in one direction. This diode matrix may be instrumental in setting status information, for example, by physically or electrically removing selected diodes from the diode matrix, for example, the PTS "wire bridge" diode for setting the pulse dial type of operation. Also the matrix relating to the key switches is used for producing status information, for example, by storing keyed-in dial information in the memory. Basically, with the diode matrix the status information is set only once, whereas this status information can be set again and again with the key switch matrix.
The keyboard means of the prior-art electronic telephone set will now be further discussed with reference to FIG. 6 of the above report. As it has been shown, and if it has not, it will be evident to those skilled in the art, the keyboard means comprises a first matrix of key switches with a respective plurality (eight, eight) of intersecting first conductors (Row 1-Row 5) and second conductors (Col 1-Col 8) and a second matrix having various (i.e. two) or a plurality respectively, (in this case eight, just like the first matrix) of intersecting first conductors (Row 6-Row 7) and second conductors (Col 1-Col 8), all second conductors of the second matrix being in common with those of the first matrix. Consequently, 2.times.8=16 setting options are realised which, for that matter, and as shown schematically, need not all be used. The control circuit comprises scanning means for reading dial information and the status information in a program-controlled fashion. The latter information determines, in a program-controlled manner, the operation of the central processor in the control circuit. So, the diode matrix can, for example, be used for adapting the electronic telephone set to specific country requirements or for manufacturing specific types of telephone sets.
As has been stated hereinbefore, the prior-art set has sixteen status options. This will cost two integrated circuit pins (see page 3 of the above publication). This is advantageous because the same resetting options would require sixteen pins when using switches such as DIP microswitches.